Guidance systems for modern aircraft require rate and acceleration sensing. Conventionally, this is achieved with the utilization of a gyroscopic multisensor assembly which operates by sensing an angular velocity about some axis perpendicular to the spin bearing axis of the device with the use of a gyroscopic element. This gyroscopic element is mechanically restrained by a piezoelectric crystal beam so that gyroscopic reaction to angular velocity mechanically strains the piezoelectric crystal beam which in turn produces an electrical output proportional to angular velocity input. Similarly, a restrained piezoelectric crystal beam can be employed to sense linear acceleration along any axis perpendicular to the spin bearing axis. Thus, through the use of one or more mechanically restrained piezoelectric crystal beams, both the angular velocity and acceleration amplitudes may be converted into electrical signals.
In may prior art devices, slip rings are employed to connect the piezoelectric crystal beam outputs with electrical processing circuits. The effect is to introduce slip ring noise into the circuits which reduces the signal-to-noise ratio, indicative of performance.
Further, prior art devices were subject to picking up spin bearing noise. This is due to the mounting of piezoelectric crystal beams along axes which were sensitive to the effects of spin bearing end play noise, again having the effect of lowering the signal-to-noise ratio.
Certain prior art attempts to rectify these problems resulted in the utilization of complex assemblies incorporating a great many parts at great expense while limiting the increase in performance.